Timing of Meals May Help or Hurt Weight-Loss Efforts, New Study Reveals

We've heard it over and over again in the weight-loss world: A calorie is a calorie is a calorie, and--despite fad diets and rumors that may claim otherwise--when you eat those calories doesn't make a difference, right? Well, as it...

We've heard it over and over again in the weight-loss world: A calorie is a calorie is a calorie, and--despite fad diets and rumors that may claim otherwise--when you eat those calories doesn't make a difference, right? Well, as it turns out, there may be some truth to the commonly supported belief that late-night eating is a dieting don't. According to a new study "late eaters" have a harder time losing weight than early ones.

First, a caveat: The study was done in Spain, where the big meal of the day is lunch, when about 40% of daily calories are consumed. (Here in the United States, a similar study may want to study early versus late dinner eaters, since our last meal is typically our largest and most indulgent of the day.) Back in Spain, researchers tracked two groups of overweight dieters, one group who tended to eat their large lunch meal before 3 p.m. and one that typically ate after 3 p.m.

After 20 weeks on their diets, people in the late-eater group had lost significantly less weight than the early-eater group; they also had lower estimated insulin sensitivity–a risk factor for diabetes. They were also more likely to skip breakfast or to eat lower-calorie breakfasts than their early-bird peers. Yet the groups were about equal in all other areas the researchers tested for, including total daily calories consumed and expended, levels of appetite hormones and sleep duration.

The research, published today in the International Journal of Obesity, is the first large-scale study to suggest that timing may also be an important part of weight-loss plans, along with total calorie intake (how much you eat) and output (how much you burn off).

The researchers aren’t sure why exactly it made a difference here, but suggest that waiting so long between breakfast and lunch–especially a small breakfast or, in some cases, none at all–can screw up the body’s circadian rhythms and cause it to metabolize food less efficiently. And that makes sense, of course: We already know that eating every three to four hours is key to fueling fat burn all day long (and from keeping us from getting hangry and binging on junk food, that is).

The total amount of calories you’re eating and burning off every day is still the most important factor in losing weight, the study authors agree–but this may be something to think about the next time you ignore your growling stomach and put off dinner until 10 p.m.

What do you think of this study–do you believe that the timing of your meals have an affect on your metabolism? Tweet us at @amandaemac and @SELFmagazine.